8

I feel like i've done this scenario plenty of times, and it usually works, so im obviously missing something.

Here's my server-side ASP.NET Button:

<asp:Button ID="btnFoo" runat="server" Text="Foo" CssClass="button foo" OnClientClick="foo_Click();" />

Which get's rendered on the client as:

<input type="submit" name="reallylongclientid" value="Foo" onclick="foo_Click();WebForm_DoPostBackWithOptions(new WebForm_PostBackOptions(reallylongclientidandpostbackoptions, false, false))" id="reallylongclientid" class="button foo">

No surprises there.

Here's the surprise, in my JavaScript function:

function foo_Click() {
   return false;
}

Okay so there's more to it than that, but i cut it down to prove a point.

When i click the button, it calls the client-side function, and returns false.

But it still posts back to the server, why?

I basically want to do this on the click of the button:

  1. Do client-side validation.
  2. If validation passes, post back
  3. If not, show some error messages on the form.

Of course, i could change this to an client-side button (input type="button") and manually kick off the postback when i want, but i shouldn't need to do that. Or should i?

RPM1984
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1 Answers1

21

write return statement so when you click on button it return false which not allow to submit form 

 <asp:Button ID="btnFoo" runat="server" Text="Foo" CssClass="button foo" 
OnClientClick="return foo_Click();" />
Pranay Rana
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  • Knew it was obvious (slaps head). Thanks. – RPM1984 Aug 06 '10 at 06:03
  • I just noticed that if i do "var passedValidation = new Boolean(false); return passedValidation" it still posts back. But if i just do return false, it doesnt. WTF? any ideas? – RPM1984 Aug 06 '10 at 06:12
  • @RPM1984: Using the `Boolean` constructor, with the `new` keyword, creates a `Boolean` *object wrapper*, and in JavaScript any object is considered to be *truthy* when used in boolean context, for example: `!!new Boolean(false)` ==> `true`, I would recommend you to simply use the boolean `true` or `false` literals, which represent directly primitive values... – Christian C. Salvadó Aug 06 '10 at 06:22
  • @CMS - yep, i figured that. well that kinda sucks, oh well - ill stick to the basic. thanks for the clarification. – RPM1984 Aug 06 '10 at 06:30